This invention relates to speed governors for a diesel engines.
Diesel engines, for example those used in large mining trucks, are commonly operated continuously between maintenance intervals. This means that the engine is left idling for appreciable periods. In order to avoid coking of the engine and to assure proper cooling, the engine must be left to idle at a higher speed than normal idle. A hand throttle is usually provided so that the operator can raise the idling speed when the engine is to be left unattended for a period of time.
However, due to warming of the engine and other factors, the idling speed can vary after the hand throttle has been set. This can result in the engine idling above or below the optimum speed. If the operator for a particular mining truck misses a shift, the truck to which he had been assigned may be left idling for the entire period until the next shift without being attended to. If the diesel engine speeds up after the hand throttle has set the high idle speed, the engine may be left racing for eight hours, resulting in damage to the engine.
Another problem with diesel powered highway vehicles is the use of the hand throttle to maintain a cruising speed. Should an emergency arise, the driver cannot stop the vehicle quickly due to the throttle being set. Although this practice by drivers is discouraged, it is still widespread.